Wood from deciduous and coniferous trees is divided into three main groups depending on the amount of heat released during combustion. The first group includes firewood with the highest thermal energy content (from 2250 to 2500 kcal/kg) and the best burning, which is obtained from trees such as maple, oak, birch and ash. The second group includes firewood produced from pine or black alder, which is characterized by a thermal energy value of 1800 to 1900 kcal/kg. The third group includes firewood produced from trees such as spruce, linden, aspen, poplar, willow and white oak, with a thermal energy content of 1500 to 1700 kcal/kg. It should be remembered that firewood from the third group should not be stored for a long time, because it can rot or return.

One of the most popular types of firewood in Lithuania is still firewood made from birch wood. They are perfect for use in fireplaces (but not biomass stoves), conventional solid fuel boilers, modern boilers, sauna heating, and cooking on the grill or in outdoor ovens.